Center Weighted Machines
Previously some electric motor driven floor polishers comprising rotating horizontal discs with polishing pads thereon were rotated less than 400 rpm, and usually, at about 300 rpm. These machines were center weighted so that their polishing pads were evenly pressed against the floor so that all of the surface of said polishing pad engaged the floor. This means that the polishing pad supported the whole weight of the polisher motor and the machine, and the pressure per square inch was evenly distributed over the whole area of the pad. Thus, if the polishing pad with this weight on the pad was increased in speed beyond 400 rpm, the operator found it difficult to control the machine, particularly when the exact parallelism of the pad with the floor was changed slightly by tilting the machine and its polishing pad, which normally occurs during operation.
Furthermore, as the speed of the evenly pressed polishing pad machine with the center weight was increased beyond 400 rpm, the electric current required for its driving motor was also increased so that normal 110-120 volt AC circuits would draw more than their fuses or circuit breakers could supply; namely, more than 15 or 20 amperes. We have also found that using a larger diameter pad at a given speed, because of the increase in peripheral speed of the polishing pad and the increase in the amount of pad contacting the floor, the ampere consumption more rapidly increased to beyond the normal fusing point of 15 or 20 amperes.